The observed winter temperatures for Turku, Finland (and also generally for North America, Europe and Russia) for the past 60 winters have been strongly dependent on the Arctic Oscillation index (AO). When the Arctic Oscillation index is in "positive phase", high atmospheric pressure persists south of the North Pole, and lower pressures on the North Pole. In the positive phase, very cold winter air does not extend as far south into the middle of North America as it would during the negative phase. The AO positive phase is often called the "Warm" phase in North America.

In this report I analyzed the statistical relation between the Quasi-Biennial Oscillation index (QBO is a measure of the direction and strength of the stratospheric wind in the Tropics), the solar activity, and the Arctic Oscillation index and obtained a statistically significant regression equation. According to this equation, during negative (easterly) values of the QBO, low solar activity causes a negative Arctic Oscillation index and cold winters in North America, Europe and Russia, but during positive (westerly) values of the QBO the relation reverses. However, the influence of the combination of an easterly value of the QBO and low solar activity on the AO is stronger and this combination is much more probable than the opposite. Therefore, prolonged low solar activity periods in the future may cause the domination of a strongly negative AO and extremely cold winters in North America, Europe and Russia.